On the damage mechanism of high-speed ballast impact and compression after impact for CFRP laminates

Hou, Yuliang Tie, Ying Li, Cheng Meng, Liang Sapanathan, Thaneshan [UCL] Rachik, Mohamed

Single and multiple track-ballast impacts are investigated for the CFRP laminates used in train carbodies. Numerical simulations have been performed to study the damage behaviors of CFRP laminates during ballast impacts and compressions after ballast impact (CABI). Intralaminar and interlaminar damages are successfully predicted using continuum damage mechanics and cohesive zone model, respectively. It reveals that, for a high-speed ballast impact, delamination occurs during the damage initiation and appears at several interfaces nearby the impacted side of the specimen. After that, fiber breakage and matrix cracking appear, while delamination continuously extends until the failure. Repeated ballast impacts on the same site and different sites of specimens show significant increase of delamination while indicating less intralaminar damage. Furthermore, CABI simulations show that, the residual compression strength decreases in a nonlinear manner with the increase of impact energy. To bear the same impact energy, less detrimental effect is caused when one impact is replaced by two or more impacts.